Nutrient recovery from urine: Urea adsorption onto biochar integrated with Na-chabazite as urease inhibitor
Bibliographic record
Abstract
This study presents an innovative technical integration for concomitant nutrient recovery from source-separated urine. While cation exchange is known for efficient K + recovery, it faces competition due to the high molarity of NH 4 + in hydrolyzed urine. This study proposes inhibiting urease activity to facilitate the recovery of K⁺ and urea from fresh urine. Na-chabazite was first proposed as a urease inhibitor in this study, reducing urease activity by 50 %. Wood biochar, with its high porosity (308.0 m²/g) and polar functional groups, shows a urea adsorption capacity of 25.4 mg/g, which can be further improved by steam activation. The isotherm analysis suggests that urea adsorption onto biochar follows a multi-layer adsorption process. Finally, an integrated process is suggested: "Na-chabazite and Biochar adsorption → urea hydrolysis → struvite precipitation + ammonia stripping-acid scrubbing", ensuring efficient recovery of urea, NH 4 + , PO 4 3- , and K + from source-separated urine.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".